The flavour of foodstuffs and beverages consists of two parts: the aroma and the taste. In general what is perceived through the olfactory epithelium in the nasal cavity is referred to as ‘aroma’, whereas the term ‘taste’ is generally used to describe the sensory impact that is perceived via the mouth, especially the tongue. The flavour sensation experienced upon consumption, especially taste, provides the final analysis of food prior to ingestion thereof. Visual and olfactory (smell) signals already give a first indication but only after intake of the food into the mouth the final decision is made either to ingest or to reject the food. Sweet taste is usually a signal that the food is safe (appetising) leading to ingestion of the food. The ‘reactions’ to salt and umami are really dependent on the strength of the signal. Bitter and sour are usually repulsive taste sensations, leading to rejection. Temperature is another measure by which the food is judged just as well as aching sensations like capsaicin (hot pepper) and certain chemicals (like carbon dioxide).
In short, this means that taste is a very important and very complex system. Until recently most flavour research was focused towards aroma. Especially the last years a series of publications relating to molecules with a (positive) contribution to the taste of foodstuffs has emerged.
Such research has been stimulated significantly by the fact that quite some receptors which are involved in the different taste sensations have been characterized by now (J. Chandrashekar et al., Nature 444, 288 (2006)).
Another interesting aspect of taste is that it can have an impact on aroma. It was reported that people having artificially sweetened water in their mouth were significantly more sensitive to the smell of benzaldehyde than people having plain water in their mouth (P. Dalton et al, Nature Neurosci. 3, 431-432 (2000)).
Several screening systems have been described that make it possible to screen, in a short time, large series of molecules for their (modulating) effect on taste response (cf. WO 04/055048, GB 2396414, WO 01/77292 and US 2004/0072254).
Most research on taste modulation so far has been devoted to taste enhancement in savoury products. Several, mainly Japanese, publications describe umami molecules, i.e. alternatives to mono sodium glutamate (MSG) (H Suzuki et al, J Agric Food Chem 50, 313-318 (2002); K Shima et al, J Agric Food Chem 46, 1465-1468 (1998); Y Ueda et al, Biosc Biotech Biochem 61, 1977 (1997)).
In EP 1291342, a ‘general taste enhancer’ is disclosed that was reported to be suitable for enhancing sweetness as well.
In patent applications WO 97/04667 and WO 04/075633 tripeptides and amino acid condensates with lactic acid and succinic acid are described that have both their own taste as well as some enhancing properties. Alpha keto acids are reported to give body and mouthfeel to foodstuffs they are added to (U.S. Pat. No. 6,287,620).
Chlorogenic acids are claimed to enhance sweetness and to reduce bitterness (WO 02/100192).
Quite a bit of work has been devoted to find bitter taste suppressors (A. N. Pronin et al, Chemical Senses 29, 583-593 (2004); EP 1401500; P. A. Breslin, Trends in Food Science & Technology 7, 390-399 (1996)).
In sweet and beverage products, further examples of the importance of the gustative dimension of flavourings have been reported. These examples include taste attributes such as bitterness, tingling and cooling-freshness.
Bitterness is an essential aspect of some food flavours, among which chocolate taste. Purine alkaloids, like theobromine and caffeine, as well as amino acids and peptides have been known for a long time as bitter substances. In British patent no. GB 1420909 it is disclosed that the bitter flavour of cocoa can be reproduced using a combination of a purine alkaloid and an amino acid or an oligopeptide which ‘produces a surprisingly more natural simultaneously bitter and astringent flavour note than either of these types of substances alone’.
Menthol, an important constituent of peppermint oil, has a strong impact on flavoured products not only because of its mint smell but also because it imparts a cooling and fresh taste. Next to mint flavoured products, it has been suggested to employ menthol in other types of flavour to impart a cool taste. US patent application no. US 2005/013846 for example discloses how menthol and derivatives thereof can be used as flavouring in water continuous spreadable acidified food products to obtain table spreads exhibiting a fresh, cool taste impression.
Similarly, cinnamic aldehyde and eugenol, constituents of cinnamon oil, are used in flavouring composition for confectionary products, not only for their smell but also because they impart a warm and tingling taste. The oral pungency of cinnamic aldehyde was described as burning and tingling by Cliff M and Heymann H (Journal of Sensory Studies 7, 279-290 (1992)). According to the same authors eugenol exhibits a long-lasting numbing effect. Cinnamon oil has been proposed as a taste improving flavouring. International patent application no. WO 90/06689 discloses that cinnamon oil, among other spice extracts, added to a minty flavour formulation, can be used to improve the long-lasting flavour of chewing-gum.
Vanillyl alcohol derivatives (e.g. vanillyl methyl or ethyl ether) are disclosed in patent US 2002/0013235 as having a strong pungent taste and warm feeling imparting effect. The same substances are described in patent JP 57082308 to be effective in increasing the refresh-feeling imparting effect of menthol. Vanillyl ethyl ether is more specifically disclosed as taste improving agent for beer in patent JP 20044229562. Substances from the same group such as vanillyl n-propyl ether are also disclosed in patent JP 57009729 as useful ingredients for salty taste.
Six different carbamic amides of vanillylamine, being structurally analogues to the pungent principle of cayenne pepper, have been tested for their properties of pungency (Lange et al.; J. Am. Chem. Soc., vol. 51, no. 6, 1911-1914 (1929). Vanillylurea, vanillylthiourea and phenylvanillylthiourea were however reported to be tasteless both as a dry powder and as an alcoholic or aqueous solution. Phenylvanillylthiourea, p-tolylvanillylthiourea and o-tolylvanillylthiourea were found to have the property of pungency but to a lesser degree than capsaicin.
Vanillyl amine and vanillyl acyl amides are also reported (U.S. Pat. No. 1,329,272) to be pungent molecules and can be used as substitutes or to fortify cayenne pepper for use in food and beverage to produce a hot or pungent taste.
N-(3-Acyloxy-2-benzylpropyl)-N-(4-hydroxy-3-methoxybenzyl) thiourea derivatives are disclosed as potent vanilloid receptor agonists and analgesics (Lee et al.; Bioorganic and medicinal chemistry 9, 9-12 (2001)). According to WO 2005/006881 these thiourea derivatives are also ligands of TRP V1 receptor, such that they would exhibit salty taste characteristics.
Derivatives of α-hydroxy carboxylic acids and purine or pyrimidines, such as GMP, AMP, CMP and IMP are disclosed in WO 2005/096843. According to said international patent application these substances are capable of modifying and complementing, the sensory impact of taste imparting substances. Thus, the present taste improving substances are advantageously applied in flavour compositions, foodstuffs, pharmaceutics, tobacco products, pharmaceutics and oral care products.
There is still a need for new substances having a positive contribution to the flavour, especially taste, of foodstuffs, beverages, tobacco products, pharmaceutics and/or oral care products they are incorporated in. One objective of the present invention is the provision of new substances and compositions that can complement and improve the impact of other flavour imparting substances, in particularly substances that have the ability to improve the impact of other flavour imparting substances at very low concentrations.